Valve means for liquid pressure systems

ABSTRACT

A valve device for use in a liquid pressure system on a vehicle to maintain the vehicle structure at a substantially constant level despite changes in the load carried thereby includes a valve spool activated by any tendency for the vehicle structure to rise or drop due to load changes to vary the liquid pressure in liquid filled struts supporting the said structure, the changes in liquid pressure also acting on a valve controlling the flow of liquid from a braking pressure source to brake motor cylinders, to provide a limit to the brake applying pressure acting in the motor cylinders which limit varies with the vehicle loading.

United States Patent Leslie C. Chouings VALVE MEANS FOR LIQUID PRESSURESYSTEMS 2 Claims, 2 Drawing Figs.

US. Cl 303/22 A,

188/195, 303/10, 280/124 Int. Cl B60t 8/18 Field of Search 280/124;

Assistant Examiner-John J. McLaughlin Attorney-Lawrence .1. WinterABSTRACT: A valve device for use in a liquid pressure system on avehicle to maintain the vehicle structure at a substantially constantlevel despite changes in the load carried thereby includes a valve spoolactivated by any tendency for the vehicle structure to rise or drop dueto load changes to vary the liquid pressure in liquid filled strutssupporting the said structure, the changes in liquid pressure alsoacting on a valve controlling the flow of liquid from a braking pressuresource to brake motor cylinders, to provide a limit to the brakeapplying pressure acting in the motor cylinders which limit varies withthe vehicle loading.

VALVE MEANS'FOR LIQUID PRESSURE SYSTEMS This invention relates to valvemeans for liquid pressure systems employed on vehicles. Liquid pressurebraking systems for vehicles are well known, and it has been proposed toprovide liquid pressure systems i in connection with the suspension ofvehicles to maintain the vehicle body at a substantially constant leveldespite variations of the static load carried thereby and variations ofload distribution due to acceleration and deceleration.

It has also been proposed to control the degree of braking on wheels ofa vehicle in accordance with the load carried by the said wheels, sothat the degree of braking increases with increasing load to takeadvantage of the greater adhesion pro vided by the greater load withoutproviding too great a degree of braking when the load is light.

It is the object of the present invention to provide a valve forcontrolling the liquid pressure in. struts or like members through whichthe weight of the vehicle is transmitted to the wheels an acting inresponse to variations in the said liquid pressure to vary the degree ofbraking applied to the said wheels.

According to the invention, valve means for the purpose set forthcomprises a valve body adapted for mounting on a vehicle structure, afirst valve device in said valve body including a valve spool slidablein a valve bore and adapted to be connected through resilient means toan axle or wheel mounting of the vehicle so as to be moved in the valvebore by relative vertical displacement of the vehicle structure and theaxle or wheel mounting, said valve spool being arranged to controlconnections between a liquid-filled strut or struts arranged between avehicle structure on which the valve body is mounted and an axle orwheel mounting to which the valve spool is connected, so as to supportat least a part of the weight of the vehicle carried by said axle orwheel mounting and a source of pressure and a drain, and to trap liquidin said strut or struts at a pressure .so related to the weightsupported by said strut or struts that the vehicle structure issupported at liquid pressure braking system between a source of liquid 7pressure and motor cylinders actuating brakes on a wheel or wheelscarried by said wheel mounting or axle and the valve member of saidsecond valve device being arranged to be urged in a valve openingdirection by the liquid pressure acting in said strut or struts and inthe closing direction by-the liquid pressure acting in said motorcylinders.

Preferably, the second valve device is mounted in the same valve body asthe first valve device.

One form of valve means according to the invention will now bedescribed, by way of example, with reference to the accompanyingdrawing, in which:

FIG. I is a diagram showing a liquid pressure system for operating thebrakes and controlling the level of a vehicle body; and

FIG. 2 is a sectional elevation of a valve according to the inventionfor incorporation in the system shown in FIG. 1.

Referring first to FIG. 1 of the drawings, a vehicle structure isindicated at 10, and two wheels of thevehicle at 11, the

wheels being mounted on an axle 12 from which the vehicle structure issupported by any convenient form of suspension system (not shown).Liquid filled struts I3, whichare arranged in series with resilientelements (not shown) of the suspension system, are arranged to beconnected through a valve unit 14 to a source of liquid pressure (pump15) so that a pressure can be maintained therein to support the vehiclestructure at a substantially constant mean level despite variations ofthe load supported by the wheels.

Brakes (not shown) on the wheels 11 are arranged to be applied by liquidpressure acting in motor cylinders. 16, liquid pressure being caused toact in the said motor cylinders 16 by operation of a driver's valve 17which controls liquid pressure supplied from an accumulator 18 in whichpressure is main Referring now to FIG. 2 of. the drawings, a valve body20,

adapted for mounting onthe body structure 10 so as to move therewithrelative to thevehicle wheels is formed with two parallel bores 21 and22. The bore 21 is closed at one end, and

is stepped intermediate its ends to provide a smaller-diameter portion23 adjacent its closed end and a larger-diameter portion 24 adjacent itsopen end. A sleeve 25 mounted in the bore portion 24 and having aninternal diameter less than that of the bore portion 23 is formedexternally with two longitudinally spaced circumferential grooves 26and27 connected respectively by radial drillings 28 and 29 to the bore ofthe sleeve 25'. The sleeve 25 is held by a clip ring against the step inthe bore 21, andthe circumferential groove 26 therein registers with apassage 31 in the valve body 20 to which is connected-a liquid pressuresupply source such as the pump 15. The circumferential groove 27registers with a passage 32 in the valve body which intersects the bore22 and is connected to the liquid-filledstruts 13 through which theweight of the vehicle body is transmitted tothe axle 12.

A valve spool'33 slidable in the bore of the sleeve 25 projects from theopen end of the bore 21 and is connected to a suitable linkage -'(FIG.1), including a lever 34 pivoted to a bracket on the valve body 20, atorsion bar 35 which is connected at one end to the end of the lever 35remote from the valve spool 33 andat its other end to one end of a linkwhich is pivotally connected at its other end to the pivotalinterconnection between a pair of limbs'36, 37 which are pivotallyconnected to the vehicle structure 10 and to the axle 12 respectively,so that the position of the valve spool 33 in the bore depends on thevertical distance between the vehicle body and the axle, the torsion bar35 tending to absorb rapid relative movements of the vehicle, body andaxle so that the valve spool33tends to respond'only to relatively slowrelativemovements.

The valve spool 33 is formed with a circumferential groove 38 which isin constant communication through the drillings 29 with the passage 32and the said valve spool carries, in the bore portion 23, a piston 39.providing a dashpot action to damp the movements of the spool. Downwardmovement of the vehicle body relative to the axle or wheel mountingtends to move the spool 33 towards the closed end of the bore 21 untilthe groove 38 connects the passage 32 to the passage 31, thus connectingthe struts 13 to the pump 15 and enabling liquid .to be fed into thesaid struts to raise the vehicle body untilthe latter is restored to itsnormal level. Upward movement of the vehicle bodyfrom its normal leveltends to move the valve spool 33 towards the open end of the bore 21until the groove 38 opens into the bore portion 24 beyond the sleeve 25and connects the passage 32 to drain port 41 communicating with thatbore portion and leading to the reservoir 19. The vehicle body is thusallowed to move downwardly relative to the wheels until, when the nonnallevel is reached, the groove 38 is again closed by the sleeve 25. Thusthe liquid pressure in the passage 32 which corresponds to the liquidpressure in the struts, is a measure of the load carried by the vehicle.

The bore 22 is also stepped to provide a portion 42 at one end ofsmaller diameter and a portion 43 at the other end of larger diameter,the passage 32 intersecting the portion 43 of the said bore adjacent thestep. The end of the bore portion 42 is connected to the drivers controlvalve 17. A plug 44 closing the end of the bore portion 43 is formedwith apertures to allow liquid from that end of the bore 22 to pass tothe liquid pressure motor cylinders 16, the pressure in which iscontrolled by the valve means. A pin 45 carried by the plug 44 projectsinto the bore portion. 43 for a purpose hereinafter described. 7

A tubular plunger 46slidable in the bore 22 has one end thereof fittingslidably in the bore portion 42, and has an enlargement 47 fittingslidably in the bore portion 43, packing rings 48 being provided on thesaid enlargement 47 and on the smaller end of the plunger 46 within thebore portion 42. A ball 49, urged towards a seat 51 in the bore of thetubular plunger 46 by a spring 52, is held ofi' the said seat undercertain conditions by the pin 45 to provide a free passage through thebore 22 for liquid in the braking system.

It will be observed that liquid pressure acting in the motor cylinders16 of the braking system will act on the full area of the plunger 46exposed in the bore portion 43, and liquid pressure acting in the struts13 will act on the annular area of the plunger 46 facing the step in thebore 22. Thus, for any given liquid pressure acting in the struts therewill be a value of liquid pressure acting in the brake motor cylindersat which the said last-mentioned liquid pressure will be sufi'icient tomove the plunger towards the smaller diameter bore portion 42, allowingthe ball 49 to seat and prevent further increase of pressure in thebrake motor cylinders 16. Thus the maximum degree of braking which canbe obtained depends on the liquid pressure in the struts l3, and sodepends on the loading of the vehicle. it will be evident that the valvemeans according to the invention will respond not only to static loadchanges, but to dynamic load changes due to acceleration or decelerationof the vehicle.

The struts 13, instead of being arranged in series with resilientelements of the suspension system and wholly supporting the weight ofthe vehicle, may be arranged in parallel with resilient suspension meanswhich support a part of the said weight, the struts being (for example)mounted within the inner diameter of coil springs providing theresilient suspension. With such an arrangement, the valve meansaccording to the invention is modified by the inclusion of a springacting on the plunger 46 in a direction to cause unseating of the ball49. The proportion of the total opening effort provided by this springis the same as the proportion of the vehicle weight supported by theassociated strut and suspension spring which is supported by thatsuspension spring.

Whilst the diagram (FIG. 1) shows a pair of wheels 11 mounted on an axle12, the valve according to the invention may be utilized in vehicleshaving independent suspension means associated with each wheel thereof,the linkage 34, 35, 36, 37 being arranged between the vehicle structureand a wheel support carrying one of the wheels.

It will be understood that the linkage 34, 35, 36, 37 is shown indiagrammatic form, andthe actual arrangement of the linkage may differsubstantially from that shown in FIG. 1. Furthermore, it will beunderstood that any other suitable resilient link may be utilized inplace of the torsion bar 35.

I claim:

1. A brake regulator system for a vehicle having a chassis with an axleand wheel mounted thereon, a hydraulic load leveling strut memberconnecting said chassis with said axle, a hydraulic brake motor cylinderfor said wheel, a source of liquid pressure and'liquid conduits incommunication with said source of liquid pressure and strut member andsaid motor cylinder, and a control valve device secured to said chassisand disposed in said conduits between said liquid pressure source andstrut member and motor cylinder comprising a housing with a first boreand a slidable valve spool therein to control the supply of liquidbetween said strut member and liquid source, said valve spool extendingout of said bore and having a linkage means connecting it to saidchassis and axle, drain port means in said bore for receiving liquidfrom said strut member, said linkage means being operatively connectedto said spool and chassis to place said strut member and liquid sourcein communication with each other when said chassis moves downwardlytoward said axle, and to place said strut member in communication withsaid drain means when said chassis moves upwardly away from said axle,and an internally stepped bore in said device in communication with saidstrut member and said motor cylinder and having a passage incommunication with said first-mentioned bore, an externally ste tubularlun er in said ste d bore and bein disix e d therein s the liquid insaid su u t member acts on th% annular area of said stepped plunger, avalve seat in said plunger with a ball valve seated thereon, biasingmeans urging said ball valve seated, a plug member on said stepped boreadjacent its end in communication with said motor cylinder having a pinextending therefrom toward said ball valve adapted to unseat it when theliquid pressure thrust in said strut member acting in one direction onsaid annular area exceeds the liquid pressure thrust acting in the motorcylinder against said plunger.

2. The system of claim 1 wherein liquid damping means are provided insaid first-mentioned bore to damp the movements of said valve spool.

1. A brake regulator system for a vehicle having a chassis with an axleand wheel mounted thereon, a hydraulic load leveling strut memberconnecting said chassis with said axle, a hydraulic brake motor cylinderfor said wheel, a source of liquid pressure and liquid conduits incommunication with said source of liquid pressure and strut member andsaid motor cylinder, and a control valve device secured to said chassisand disposed in said conduits between said liquid pressure source andstrut member and motor cylinder comprising a housing with a first boreand a slidable valve spool therein to control the supply of liquidbetween said strut member and liquid source, said valve spool extendingout of said bore and having a linkage means connecting it to saidchassis and axle, drain port means in said bore for receiving liquidfrom said strut member, said linkage means being operatively connectedto said spool and chassis to place said strut member and liquid sourcein communication with each other when said chassis moves downwardlytoward said axle, and to place said strut member in communication withsaid drain means when said chassis moves upwardly away from said axle,and an internally stepped bore in said device in communication with saidstrut member and said motor cylinder and having a passage incommunication with said first-mentioned bore, an externally steppedtubular plunger in said stepped bore and being disposed therein so theliquid in said strut member acts on the annular area of said steppedplunger, a valve seat in said plunger with a ball valve seated thereon,biasing means urging said ball valve seated, a plug member on saidstepped bore adjacent its end in communication with said motor cylinderhaving a pin extending therefrom toward said ball valve adapted tounseat it when the liquid pressure thrust in said strut member acting inone direction on said annular area exceeds the liquid pressure thrustacting in the motor cylinder against said plunger.
 2. The system ofclaim 1 wherein liquid damping means are provided in saidfirst-mentioned bore to damp the movements of said valve spool.